This invention relates to an electronic filing device and in particular to an electronic filing device, which is suitable for synthesizing and displaying an image by a personal computer, etc. on a high resolution CRT device for image data display.
An electronic filing device is a device, which scans a drawing or a document with means such as a photoelectric transforming device, etc.; accumulates obtained image data in an optical disk, etc.; and outputs them to a CRT, a printer, etc. or needed. It is found that the control section of most of these kind of devices is provided with a microprocessor for universal use and has the same construction as a usual personal computer or a workstation. For this reason, in the present situation it is strongly desired to realize a usual workstation, i.e. table calculation or word processing function with an electronic filing device, when it is not used as an electronic filing device.
Therefore a prior art device is so constructed that, as discussed in "Office Work Control", Vol. 25, No. 3 (1986) pp 23-28, in order to realize a multi-functional electronic filing device, the electronic filing device is connected on-line or off-line to a personal computer and the former is in charge of the processing function of the image data, while the latter is in charge of the extension function of the former. Here the extension function is one, which has been realized heretofore by a personal computer, such as a table calculation or a word processing function, etc. Further the word "on-line" means a configuration of various electronic devices connected according to a communication type such as RS232C, token ring LAN, etc., while the "off-line" indicates a configuration, by which information is exchanged through a medium such as a floppy disk, etc.
As described above, in a prior art device, in order to realize the multifunction, the electronic filing device and the personal computer are neither modified from the point of view of hardware nor from the point of view of software. For this reason the method, by which the electronic filing device is connected to a personal computer, is widely spread as an extremely realistic method.
On the other hand, apart from the electronic filing device, directing attention to the method for displaying images on the screen of a CRT, a prior art device disclosed in Japanese Patent Unexamined Publication No. 59-105682 is known. This device superimposes an image inputted by a television camera on an image on a CRT from a computer, etc. to display them, The device is composed of a video RAM capable of storing image data of the two systems, an OR circuit synthesizing these outputs and a group of control circuits controlling them.
The work of this device will be briefly explained. At first information coming from the computer, which constitutes most of an image, is stored in a first video RAM. At the same time the signal coming from the television camera, etc. is stored in a second video RAM in synchronism with the fundamental clock of a display system. Next the image signals coming from these two video RAMs are outputted to the CRT through an OR circuit. Finally the two images are displayed and synthesized on the screen of a CRT.
As stated above, the second prior art device can synthesize and display two images on the screen of a CRT with an extremely high efficiency.
According to the first prior art each electronic filing device and personal computer has a CRT exclusively used therefor. Since there are disposed two CRTs displaying different images in one system and the user must pass judgment, while locking at two displays on these two CRTs, it has a problem that the operability thereof is poor. Further it has another problem that the area occupied by the device is large because of the two CRTs. In addition, since the system is so constructed that two microcomputers having similar functions are each is disposed in the electronic filing device and the personal computer system. The electronic filing device is controlled by its microcomputer by using a program different from that of the personal computer, and the electronic filing device and the personal computer are connected with each other through a communication line. The system has an economic problem from the point of view that two microcomputer systems are required in the control system and also from the point of view that different programs have to be separately made for the electronic filing device and for the personal computer system in order to effect a new program processing, which is to be carried out.
The second prior art technique is improved with respect to the first by the fact that image information of the electronic filing device and image information of the personal computer are displayed on one CRT. However, since the resolution power of the high resolution CRT in the electronic filing device and that of the CRT in the personal computer differ significantly from each other, the image information of the personal computer is displayed on the screen of the high resolution CRT as an extremely small image, which gives rise to a problem that the whole image is difficult to see. In addition no measures for enlarging the image of the personal computer were taken.